The crowns of your aquarium snails shells are rotting and the dying?

Snails need calcium to build and maintain their shells. A lack of calcium in the water causes the crowns of their shells to rot and the snails eventually die. To prevent this, add a calcium supplement to the water, such as crushed cuttlebone or calcium carbonate. You can also provide the snails with food that is high in calcium, such as vegetables or shrimp.